package network;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: GodK
 * Date: 2024-09-04
 * Time: 12:25
 */
public class EchoServer {
    private ServerSocket serverSocket = null;

    public EchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }

    public void start() throws IOException {
        System.out.println("启动服务器");
        while (true) {
            Socket clientSocket = serverSocket.accept();
            Thread t = new Thread(() -> {
                try {
                    processConnection(clientSocket);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            });
            t.start();
        }
    }

    private void processConnection(Socket clientSocket) throws IOException {
        // 先打印一下客户端的信息
        System.out.printf("[%s:%d] 客户端上线!\n", clientSocket.getInetAddress(), clientSocket.getPort());
        // 获取到 socket 中持有的流对象.
        try (InputStream inputStream = clientSocket.getInputStream();
             OutputStream outputStream = clientSocket.getOutputStream();) {
            Scanner scanner = new Scanner(inputStream);
            PrintWriter printWriter = new PrintWriter(outputStream);
            while (true) {
                // 1. 读取请求并解析
                if (!scanner.hasNext()) {
                    // 如果 scanner 无法读取出数据, 说明客户端关闭了连接, 导致服务器这边读取到 "末尾"
                    break;
                }
                String request = scanner.next();
                // 2. 根据请求计算响应
                String response = process(request);
                // 3. 把响应写回给客户端
                printWriter.println(response);
                printWriter.flush();
                // 4. 打印日志
                System.out.printf("[%s:%d] req=%s; resp=%s\n", clientSocket.getInetAddress(), clientSocket.getPort(),
                        request, response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            System.out.printf("[%s:%d] 客户端下线!\n", clientSocket.getInetAddress(), clientSocket.getPort());
            clientSocket.close();
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        EchoServer server = new EchoServer(9090);
        server.start();
    }
}
